Fowler, the CD300 is a pile of shit. Its a cheap head unit with a nak facia! For a start it only has a 1 Bit D A converter (the sound processor), its the CD400 or CD500 that are propper Naks with 24 Bit D A converters and much better spec. Both the 400 and 500 have an Aux input so you can run a ipod but only the 500 plays MP3 discs but yes they do look OEM ish and are one of the best head units for sound quality.
I have a CD500 for the sport.
Ash, as for speakers, the E30 saloon uses 13cm front and rear. The problem with the position of the fronts isn't just the poor location for sound quality, the recces isnt very deep either so speakers with a huge magnet wont fit here.
Rears are a bit better as the hole is deeper but if you can, try and get some of these as you can replace the original components with some newer ones. They were an option on E30 saloons which made part of the Hi Fi pack which included the tweeters in the front and a seperate amp.
Agreed that to make the most of the speaker a small 4 chanel amp should be used and there are places to hide it all. This is exactly what i have gone for and the only thing that is visible thats not oem is the head unit.
As for speakers, Alpine, Focal, MB quart, diamond audio, DLS are what you should be looking at.
http://www.caraudiodirect.co.uk/speaker ... -13cm.html
This is the amp im using as the PDX amps are small and their design means that heat isnt and issue so location isn't as important as a conventional amp so much so that they can be stacked on top of each other.
http://www.caraudiodirect.co.uk/alpine-pdx-4-100.html
Any questions just shoot me a PM Ash. HTH